There is a fair bit of confusion out there around three terms:
2. Common descent
3. Universal common descent
The recent announcement of a rethink evolution conference sponsored by the Royal Society in London in November has meant that many people now know about the growing problems with the textbook Darwinism we learned in school.
But confusion among terms can turn productive discussions into shouting matches. Here are some conversation pointers that I have found helpful:
1. Evolution: Life forms can alter greatly over generations, and in many cases permanently.
At one time, Darwinism (natural selection acting on random mutation) was the default explanation of evolution (often functioning in place of a plausible explanation). That theory, credited to Charles Darwin, attributes evolution to small, accumulated random changes that happen to confer a survival advantage on a life form. The life form then passes on these altered genes. Over time, the accumulated small, possibly reversible, changes become big, irreversible ones.
The advantage of Darwinism is that it is easy to understand and assimilate into popular culture, including art, literature, and pop psychology . The disadvantage is that it has been hard to document as a fact. Even iconic examples like the supposed evolution of the beaks of Darwin’s finches have turned out not to be permanent changes.
More significantly, in recent decades, we have learned about a number of ways evolution can happen: convergence on a common goal, horizontal gene transfer, epigenetics, devolution, self-organization, genome doubling, hybridization, jumping genes, and symbiosis.
In other words evolution happens*, but not usually the way the evolution experts have said.
Clearly it’s time to start listening to the fossils again.
* If a person believes that life forms cannot, in principle, change permanently over generations, then the onus is on them to explain why they know that can’t happen.
2. Common descent:A given life form goes back through a very long line of ancestors to an earlier, perhaps simpler life form. That seems eminently reasonable in principle, but the family tree has often proven difficult to reconstruct. The molecular clock, as it is called, is often a poor fit with the fossil record. And convergence of different life forms on the same strategies produces many surprises.
The truth is, we don’t know very much yet. Sometimes the argument for common descent amounts to “Believe it because it is Science! After all, things couldn’t have happened any other way except by Divine Intervention!” Which is why I like to avoid arguments about common descent as a dogma of some kind, and concentrate on specific situations for which we have reliable information.
3. Universal Common Descent (UCD): All life originated in a single cell that accidentally came together billions of years ago in the ocean. That belief is simply an article of faith. We don’t know and probably don’t even have a way of knowing. Prominent figures like Carl Woeseand Craig Venter, for example, don’t think the evidence shows that all life descends from a single cell.
In any event, we now find ourselves in the origin of life (OOL) controversy, where things are much murkier than in most chapters of the history of life to date. There are so many competing schools of thought on OOL that dogmatism is, among other things, a social sin.
I have found that taking the time to outline the issues in this way helps circumvent Darwin bullies. They take control of a conversation to announce that they have the answer, others don’t know anything, those who disagree have unworthy motives, Darwin has triumphed over God, Jesus loves Darwin and so should you, etc., etc.
They got away with that stuff for decades, but now they may as well be saying:
My name is Used-to-was,
I am also called Played-out and Done-to-death,
Note: News posting light until later this evening, due to O’Leary for News’ current alternate day job.
See also: What we know and don’t know, about the origin of life